100 Summer Days of Nostalgia. A special event in 2011 where 100 older Half-Life maps and mods were played or replayed. For more details. see the event’s dedicated page.

After proving your skill and cunning by escaping the Black Mesa complex alive, you have been called on by a shadowy organisation – the Alien Counter-Insurgency Bureau – to help protect mankind from the threat posed by Xen.

Tonight, the A.C.I.B. has need of your special abilities to counter a new threat to civilisation. You have been given a rendez-vous in the warehouse district of the city to receive your mission briefing.

The terraformation of Xen has begun. The planet now supports a breathable oxygen-nitrogen atmosphere and earth-like gravity. A scientific facility called the Xeno Project has been set up on the planet for continuing research into portal technology. Tension on the planet is running high due to the secrecy surrounding the project and the military’s distrust of the scientific community.

You are Gordon Freeman. Your mission is to report to the underground test lab at the Xeno Project.

Your name is Mark Hunt, an elite Marine sent in to ‘clean up’ the Black Mesa Incident. Near evening your platoon was ambushed by a superior force, taking you completely by surprise. In the chaos you became separated from your C.O. and by sheer luck evaded the atomic blast that followed. The Brass didn’t call it luck. You were courtmartialed for desertion and sentenced to ten years in a maximum security prison. Two years into your sentence, something happened…